Aramco develops hybrid engine that could eventually run on hydrogen

The world's largest oil producer developing a brand-new, highly efficient combustion engine might seem ironic at first glance. But Aramco's Dedicated Hybrid Engine — the DHE — is technically remarkable, and for hydrogen enthusiasts there is an extra detail worth noting: the engine has been designed with hydrogen as a potential future fuel.

What is the DHE?

The DHE is a naturally aspirated 1.6-litre three-cylinder engine developed by Nayan Engineer (the name is not a joke) at Aramco Americas' Detroit Research Center, in collaboration with French motorsport firm Pipo Moteurs. But the interesting part is not the displacement — it is the philosophy.

Where hybrid engines are traditionally adapted from existing petrol engines that are retrofitted with electrification, the DHE was engineered from a clean sheet as a hybrid engine. It is never meant to drive a vehicle on its own: it works exclusively as a generator and power source for an electric drivetrain. That distinction makes a world of difference for efficiency.

The technical cleverness

The engine always runs within a narrow, optimal rev range — its so-called 'efficiency island' — leaving all dynamic tasks to the electric motors. That makes expensive, complex components like variable valve timing or a turbocharger redundant.

Other notable design choices:

• Cam-in-block pushrod design (simpler and more compact than modern DOHC engines)

• Monoblock casting with no separate cylinder head

• Roller bearings on the crankshaft, camshaft and connecting rods for minimal friction

• Crankshaft offset 12 mm from the cylinder centreline, reducing side forces on the pistons

• Combined direct and port fuel injection

• High compression ratio with late intake valve closing

The result: thermal efficiency of 41 to 42 percent. For comparison, most combustion engines achieve 20 to 40 percent. Aramco's own calculations point to 35 percent less fuel consumption versus a conventional four-cylinder in a mid-size sedan — for a price premium of just $3,800.

The drivetrain: Toyota, but different

Planetary gearsets are positioned at both ends of the crankshaft, each coupled to a motor-generator. This creates an electronically controlled CVT-like behaviour, similar to Toyota's Hybrid Synergy Drive — but without a conventional gearbox or differential. The system is not only more efficient but reportedly around 20 percent cheaper than comparable Toyota hybrid setups.

And then: hydrogen

The most significant detail for H2 Rijders readers appears almost as a footnote in the technical documentation: Aramco is exploring hydrogen as a future fuel for the DHE. This is not idle speculation — it fits a broader logic. The engine is already designed for use as a range-extender in an electric vehicle, an application where a hydrogen combustion engine is technically well suited. Hydrogen burns cleanly, and combined with an electric drivetrain, emissions are minimal.

Other future improvements under investigation include pre-chamber ignition, a higher compression ratio (up to 15:1) and axial-flux electric motors.

Strategic or genuine?

It is tempting to read the DHE purely as Aramco's attempt to keep the combustion engine — and thus demand for fossil fuels — alive as long as possible. That motivation undoubtedly exists. But the technology itself is genuinely innovative. An engine with this efficiency, designed as a range-extender and compatible with hydrogen, fits neatly into the transition to zero-emission transport — particularly for regions where charging infrastructure is lacking or where heavy transport demands long range.

The patent was filed in February 2026. Aramco is now looking for automotive partners willing to take the engine into mass production.

Sources:

• Autoblog.nl – Oliebedrijf Aramco vindt verbrandingsmotor opnieuw uit (18 April 2026)

• Aramco Americas – When efficiency meets exciting (February 2026)

• MotorTrend – Aramco Built a Hybrid to Beat Toyota

• CarBuzz – Big Oil Just Built a Hybrid Engine That Embarrasses Mainstream Automakers